The present invention relates generally to the field of digital images, such as still pictures, video, film, multi-media, individual frames of such content, and so forth. In particular, the invention relates to the placement, detection, and/or preservation of digital watermarks in three-dimensional (3D) images, particularly those converted to such formats from two-dimensional (2D) digital content.
Visual content has been provided to audiences for centuries in various forms and for various purposes. Physical supports for such content have included canvas, hard supports (e.g., paper, board, etc.), and more recently, film. As a result of this long history, a vast pool of content exists that can be accessed by potential audiences and consumed or otherwise enjoyed through theaters, museums, various entertainment outlets, and so forth. Increasingly, however, such content is available online and virtually independent of any common viewing schedule as was the case in conventional cinemas.
Some decades ago advances were made in the presentation of stereoscopic images that were either separate or overlaid (superimposed and integrated) on one another and that were often viewed by special apparatus (e.g., glasses), to create the illusion of three dimensions. 3D presentations of multimedia content were often an entertaining novelty and little more. More recent developments in the technology, however, have resulted in much more convincing and compelling representations that are appreciated by audiences, primarily in cinemas. However, other playback media are rapidly evolving, including televisions, monitors, and so forth that could lead to a significant movement towards the presentation of entertainment content in 3D. Other reasons for 2D to 3D conversion include the substantially reduced costs of creating content in 2D as compared to 3D, as well as the ability to reuse existing 2D products. These developments, in combination with the existence of literally hundreds of thousands or millions of content items in legacy libraries are leading to a drive toward conversion of conventional 2D content to 3D.
For a number of reasons, digital watermarks are used in 2D digital content, such as still pictures, video, movies, multi-media presentations, and the like. Such watermarks may be visible and apparent to a user, such as a network icon in the corner of a television program. Other watermarks are not readily discernible by the viewer, and may serve various functions, such as to provide an indication of the source of origin of the content. Watermarks of the latter type may include so-called forensic marks, which may be used to trace content, to provide appropriate authorization for the reproduction of content, and to allow for at least some control of the unauthorized reproduction and dissemination of content. In all such cases, however, the watermark must remain detectable in the content and, where the watermark contains specific information, it must be appropriately readable at least to a degree that will allow reference to known sources, identifying materials, and the like.
A problem that will arise in the conversion of 2D content to 3D content which will affect the detectability and discernability of watermarks in the 3D content. In particular, watermarks in content converted from 2D to 3D may not be preserved or may be shifted (i.e., relative to the location of the watermark in the 2D content) to locations where they may not be easily detected. Accordingly, there is a need in the field for new techniques that will allow for verification of the detectability of a watermark in 3D content. There are also needs for improved systems for placing watermarks in 2D and/or 3D content.